A runner runs in the following pathway: A->B->C->D->A. He finishes it within 4 seconds.

Speed = 12 / 4 = 3m/s

Velocity = 0 / 4 = 0 m/s

Note(1) The speed and velocity calculated above are actually the average speed and average velocity for the whole journey. (2) When the speed of an object is a constant, its velocity may not be a constant as it can change its direction.(3) When the speed of an object changes, its velocity also changes.(4) When the velocity of an object changes, its speed may not change as the object can change direction without changing the speed to change its velocity.